Big brother is a legendary swordsman while little sister is a talented archmage.

Set in a fantasy world where magic and monsters exist, both siblings are supremely overpowered and deeply in love with each other. The story follows the duo’s admission to a prestigious magic university, Temple Academy.

Personal problems. Old dramas. New friendships. Together, Onii and Amae adjust to their new school life and experience the emotional rollercoaster that is the next chapter of their lives.

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Dec 27, 2018: The title of the story hooked me in just from the sheer strangeness of it, but I wasn’t sure what to expect with what to find within. The description makes it very clear that the story’s going to be the kind of "magic school with a powerful main character and usually some incest themes" fantasy story that’s popular in Japanese books and anime these days. That is not a niche I care for whatsoever, unless it’s done very well.

This was not done very well.

"A Sister’s All You Need" prides itself on advertising its taboo sibling relationship and makes that the focal point of the story, but it’s not like Japanese light novels don’t already have a lot of brother-sister relationship stuff to begin with. In the end that focus is exactly what cripples the story from providing any real entertainment value, because everything else within is the absolute most basic-tier generic nothingness.

So far there have been three complete story arcs. The first of these, "Potentials and Regulars," starts out with massive infodumping about this magic society where there’s tiers of adventurerers and tiers of magic and tiers of weapons . . . and now the main brother and sister Onii and Amae are attending a magic school where there’s a bunch of tiers. So many rankings and levels to the point that it’s mindboggling.

(By the way, if you aren’t in on the joke, "Onii" means "older brother" in Japanese, and "Amae" means "relying on others." This summarizes their entire character arcs pretty neatly.)

So the story follows Onii and Amae as they enter magic school and are way powerful and revered and everybody loves them. There’s one obligatory fight scene to establish that Onii is the best fighter in the school, but other than that it’s just introductions. Then comes the second story arc . . . With more infodumping. More tiers. More new characters that have some backstory history with the duo.

And we get to learn that Onii and Amae, famous as extremely powerful magicians, have a secret identity that they are hiding from the world . . . they are Yin and Yang, the two most powerful magicians ever who are two of the only four Hero Tier (that’s above Adamantium Tier) heroes on the planet. . . . Yes. It’s as if Superman’s secret identity was Clark Kent, but Clark Kent was a world-famous MMA fighter. They’re so powerful that nobody is remotely a threat to them, removing all tension (at least as far as the story has progressed).

The author clearly loves playing around with the taboo fact that the brother and sister are in love and make out all the time. It’s downplayed earlier in the story, but by the middle of the second story arc (where there is a graphic sex scene), they drop the pretense of tension and have them constantly talk about their relationship together. They kiss in the middle of a fight scene at one point partly to confuse the other characters around them. It is what it is. But it means that everything else in the story is downplayed— we don’t get to see much of the world the author has created, and all of the side characters so far are underdeveloped. Even Onii and Amae themselves, unable to be apart for more than a single chapter at a time, lack any defining personality traits that I can pinpoint, even just having caught up on it today.

There are points in this story where I legitimately started to wonder whether this was actually a parody of these sorts of stories— Amae goes undercover after a big buildup about how dangerous her secret mission is . . . and is captured the next chapter. There’s a sword that apparently retroactively erases people from history. A side chapter has Onii reading "A Sister’s All You Need" on his computer. I’m PRETTY sure that it isn’t parody, but I haven’t been able to confirm either way.

From the three story arcs so far, the story hasn’t progressed but actually gone backwards— the second story arc is entirely exposition about the main duo’s past, and then the third story arc is literally a flashback to establish their relationship with another character. I’m hoping that this changes as the next story arcs occur, but the author has reader polls after each arc and the current poll has "Add More Wincest!" at over 50% of the vote, so I’m worried that there will merely be more brother-sister makeouts and even less plot.

Since "A Sister’s All You Need" is an ongoing serial, I am really hoping that the story improves in future story arcs by forging its own, original path instead of wholesale copying the Japanese Light Novel template. Invincible characters are boring. Undynamic characters are boring. Infodumping without showing the world in a present-tense context is boring. So far that hasn’t been the case, but the author seems very nice (from the chapter notes and afterwords) and their writing has been improving with each chapter. So we’ll have to see in a few months/years how things have changed after these first three story arcs.

But until then, I have to say I can’t recommend the story to anyone, even people who enjoy Light Novel-style action stories or MMORPG-style fantasy stories.